The microbial diversity of the Su Bentu cave, Italy and the influence of human exploration.

Introduction: The microbial diversity in the Su Bentu Cave (Sardinia, Italy) was investigated by means of Illumina MiSeq analysis. The hypogean environment is of great interest for astrobiological research as cave conditions may resemble those in extra-terrestrial regions. Furthermore, they hold high potential to identify novel, extremely adapted organisms to severely oligo-trophic habitats. However, the influence of human is not neglectable and in-depth investigations are needed to determine the impact of exploration on an otherwise mostly pristine ecosystem. The cave investigated in this study develops for several kilometres into the mountain, two hundred metres below the topographic surface and is characterized by a strong air circulation. Its structure is composed of huge passages carved in limestone where an ephemeral underground stream creates some lakes, close to which seven samples of visible calcite rafts, manganese deposits and moonmilk (a hydrated calcium carbonate speleothem), were sampled during an expedition in 2014. Other samples were re-trieved from a frequently used campsite and from some dry cave passages leading deeper into the cave

Subset currents on free groups

We introduce and study the space of \emph{subset currents} on the free group $F_N$. A subset current on $F_N$ is a positive $F_N$-invariant locally finite Borel measure on the space $\mathfrak C_N$ of all closed subsets of $\partial F_N$ consisting of at least two points. While ordinary geodesic currents generalize conjugacy classes of nontrivial group elements, a subset current is a measure-theoretic generalization of the conjugacy class of a nontrivial finitely generated subgroup in $F_N$, and, more generally, in a word-hyperbolic group. The concept of a subset current is related to the notion of an "invariant random subgroup" with respect to some conjugacy-invariant probability measure on the space of closed subgroups of a topological group. If we fix a free basis $A$ of $F_N$, a subset current may also be viewed as an $F_N$-invariant measure on a "branching" analog of the geodesic flow space for $F_N$, whose elements are infinite subtrees (rather than just geodesic lines) of the Cayley graph of $F_N$ with respect to $A$.Comment: updated version; to appear in Geometriae Dedicat

Characterization of surficial weathering on calcarenite rocks in the rupestrian system of "San Michele delle Grotte" in Gravina in Puglia (Bari, Apulia)

San Michele delle Grotte is a rupestrian cave excavated into the “Calcarenite di Gravina” formation, resting over the Cretaceous formation of the “Calcare di Altamura”. The artificial cavity develops exactly at the contact between the two lithologies, with the first making the walls and vault, and the second being the pavement. Both formations are characterized by discontinuities and show evident instability features and surficial rock weathering. In particular, patinas and crusts extensively cover the walls, ceilings, and fractures inside the cavity. In the present study, a complete mineralogical and morphologic characterization of selected rock samples was carried out in order to assess the link between petrographic and mineralogical features of calcarenite and the weathering mechanisms and, specifically, to define the intensity of both the biotic and abiotic processes. Unaltered and weathered samples of Calcarenite di Gravina were analyzed through optical microscopy, scanning electron microscopy (SEM), and X-ray powder diffraction (XRPD). In thin section, we observed bioclastic packstone to grainstone fabrics, the samples containing microfossils as foraminifera, bivalve shells fragments, and bryozoans. Overall, the unaltered rock is composed of calcite, aragonite, ankerite, and subordinate quartz. In its surficial portion it is possible to find different types of alterations which can be divided into two main groups: group 1 encompasses rock samples with black to green biological coatings; group 2 includes salt-weathered rocks. Group 1 is dominated by algae constructive and destructive features, and from the mineralogical standpoint it contains calcite and minor quartz and gypsum; group 2 evidences efflorescence crusts (crusty white mineral salts) which are dominated by sulfates such as syngenite (K2Ca(SO4)2•2H2O), gypsum (CaSO4•2H2O) and arcanite (K2SO4), and other salts including niter (KNO3) and sylvine (KCl). Scanning electron microscope images allowed to observe a distinctive enhance of microporosity on the rock surface immediately at the contact with the biological structures and efflorescence crusts. The results of our investigation highlight a higher abundance of biological coating where the host rock is well exposed to light, as well as the occurrence of efflorescence crusts which can originate from both anthropogenic air pollution (wet and dry airborne deposition that provides sulfate and nitrate anions) and circulation of soil water whose composition can be modified, for instance, by fertilizing

Dissolution-corrosion measurements with limestone and gypsum tablets in active sulphuric caves of southern Italy

Dissolution‐corrosion (DC) represents an important factor for speleogenesis, and can be measured monitoring weight variation over time of carbonate and gypsum tablets exposed in underground environments. The oxidation of H2S produces H2SO4, which in carbonate host rock induces the surface of carbonate tablets to be rapidly corroded by sulphuric acid, whereby CaCO3 is replaced by CaSO4∙2H2O, producing a significant weight gain. We describe preliminary results of DC monitoring in four still‐active SAS systems, including Ninfe Cave and Terme Sibarite (Calabria), Fetida Cave (Apulia), and Acqua Fitusa Spring Cave (Sicily). The tablets have been set inside the caves, in three different conditions of exposure (i.e. underwater, air, interface zone) in the winter 2015‐2016 to monitor DC in five years. The results show how the condition of exposure is an important control for the behaviour of weight variation. Tablets set underwater displayed significant weight loss during the first period of exposure, whereas those located at the interface zone exhibited a tendency of weight variation significantly dependent on time, and tablets in air showed weight gain

Right ventricular dysfunction and dyssynchrony after surgical repair of tetralogy of fallot: a three-dimensional and speckle tracking echocardiographic study

Background. Prolonged QRS duration and mechanic-electrical interaction are markers of increased sudden death risk in tetralogy of Fallot (TF). The combined effects of preoperative hypertrophy and hypoxia, possible intraoperative myocardial damage, type of reconstruction, and acquired postoperative lesions such as pulmonary regurgitation may result in impaired RV deformation. Recently speckle tracking echocardiography (STE) has been proposed to assess mechanical dyssynchrony in these patients but the role of electromechanical dysfunction is not completely clear. Methods. Fifteeen patients after TF repair (aged 17-51years) with dilated right ventricle, right bundle branch block (QRS 120ms), and NYHA class I or greater were studied with two-dimensional and three-dimensional echocardiography (3DE) and STE. Right ventricular volumes and right ventricular ejection fractions (3D-RVEF) were obtained. Right intraventricular dyssynchrony was determined as the difference between the longest and shortest electromechanical coupling times in the basal septal and lateral RV segments. Interventricular dyssynchrony was determined as the difference between electromechanical coupling times in the basal lateral LV segment and the most delayed RV segment. Fifteeen age-matched healthy subjects were selected as controls. Results. Right intraventricular dyssynchrony (76.223.8ms vs 12.79.1ms) and interventricular dyssynchrony (75.224.3ms vs 11.38.2ms) were shown in patients compared to normal controls. Right intraventricular dyssynchrony correlated with RV longitudinal strain, 3D RV end-systolic volume, and QRS duration. Interventricular dyssynchrony correlated with RV longitudinal strain , RV systolic pressure, 3D-RVEF, and QRS duration. Reduced RV strain, 3D-RVEF and prolonged QRS duration were the main determinant factors predicting dyssynchrony by multivariate analysis. On ROC curves RV strain and 3D-RVEF had optimal predictive accuracy of the NYHA functional class and a larger area under the receiver operating characteristic curve than the QRS duration. Conclusions. RV systolic dysfunction and dyssynchrony can be identified in patients with repaired TF by 3DE and STE. Dyssynchrony is associated with reduced 3D-RVEF and RV myocardial deformation

Analysis of valvar and left ventricular parameters in infective aortic endocarditis as predictors of outcome: a combined assessment by transesophageal and strain echocardiography

Purpose. The timing of surgery is crucial for patients with aortic endocarditis in whom medical therapy fails. The aim of our study is to identify potential echocardiographic "markers" of adverse events in patients with aortic regurgitation from infective endocarditis. Methods. Fifteen patients with aortic regurgitation (AR) from infective endocarditis were studied by transesopageal echocardiography (TEE) and transthoracic speckle tracking echocardiography (STE). Fifteen healthy subjects were selected as controls. Vegetation size was assessed by TEE. Standard transthoracic echocardiographic parameters were determined. Global left ventricular (LV) longitudinal strain (LS), radial and circumferential strain were measured by STE. Averaged LV rotation and rotational velocities from the base and apex were obtained and used for calculation of LV torsion (LVtor). Mitral annular velocities were also obtained by tissue Doppler imaging (TDI). Results. Mean percentage intraobserver variability was 6% for LV-LS and 8% for LV-tor, and mean percentage interobserver variability was 11% for for LV-LS and 12% for LV-tor. Severe AR had decreased LS compared with control subjects. LVtor decreased significantly in severe AR compared to normals (p<.001) as a result of a predominant decrease in apical rotation. By multivariate analysis, LV-LS (p=0.03), LV-tor (p=0.008) and vegetation size (p=0.009) were predictive of adverse events. ROC curves suggested that thresholds offering an adequate compromise between sensitivity and specificity for adverse events detection were -18.4% for mean global LV-LS (AUC .76), 12mm for vegetation size (AUC .84), and 19.7degrees for LVtor (AUC .89). The combination of vegetation size and LVtor had the highest diagnostic accuracy for identifying adverse outcome, superior to vegetation size (p=.008) or LVtor alone (p=.026). Conclusions. The combined evaluation of the characteristics of vegetating masses and LV function strain parameters improve the sensitivity of echocardiographic indices in predicting cardiac morbidity and mortality of aortic regurgitation from infective endocarditis

Secondary Minerals From Italian Sulfuric Acid Caves

Italy is a country hosting a large number of hypogenic sulfuric acid (SAS) speleogenesis caves, mostly located along the Apennine chain, but also in Campania (along the coastline of Capo Palinuro), Apulia (along the coastline of Santa Cesarea Terme) and Sicily. Besides the typical morphologies related to their special geochemical origin (cupolas, replacement pockets, bubble trails, etc), these caves often host abundant secondary mineral deposits, mainly gypsum, being the result of the interaction between the sulfuric acid and the carbonate host rock. Native sulfur deposits are also well visible on the ceiling and roof, and peculiar sulfuric acid minerals such as jarosite, alunite, and other sulfates like copiapite, pickeringite, tschermigite, tamarugite (probably related to the weathering of native clay minerals) have been found in those caves. The presence of typical SAS minerals, together with the morphologies, testifies the influence of rising acidic waters, that likely interact with the deep-seated Triassic evaporite deposits (along the Apennine chain), with volcanic sources or hydrothermal springs in the Tyrrhenian sea (in Campania) and with marine waters that infiltrate on the sea bottom and rise through deep faults (in Apulia). This paper describes the secondary minerals discovered in several caves, and discusses their origin and possible use in reconstructing the evolution of these cave systems

Assessment of severity of mechanical prosthetic mitral regurgitation by transoesophageal echocardiography

Objective: To evaluate the ability of colour Doppler transoesophageal echocardiography (TOE) to assess quantitatively prosthetic mitral valve insufficiency. Methods: 47 patients were studied with multiplane TOE and cardiac catheterisation. Proximal jet diameter was measured as the largest diameter of the vena contracta. Regurgitant area was measured by planimetry of the largest turbulent jet during systole. Flow convergence zone was considered to be present when a localised area of increased systolic velocities was apparent on the left ventricular side of the valve prosthesis. Pulmonary vein flow velocity was measured at peak systole and diastole. Results: Mean (SD) proximal jet diameter was 0.63 (0.16) cm, with good correlation with angiographic grades (r  =  0.83). Mean (SD) maximum colour jet area was 7.9 (2.5) cm(2) (r  =  0.69) with worse correlation if a single imaging plane was used for measurements (r  =  0.62). The ratio of systolic to diastolic peak pulmonary flow velocity averaged 0.7 (1.3) cm (r  =  −0.66) with better correlation (r  =  −0.71) if patients with atrial fibrillation were excluded. Mean (SD) regurgitant flow rate was 168 (135) ml/s and regurgitant orifice area was 0.56 (0.43) cm(2), with good correlation with angiography (r  =  0.77 and r  =  0.78, respectively). Conclusions: TOE correctly identified angiographically severe prosthetic mitral regurgitation, mainly by the assessment of the flow convergence region and the proximal diameter of the regurgitant jet

Le cavità sotterranee del territorio pugliese, un patrimonio culturale-architettonico da valorizzare: il progetto di ricerca PRIORITA’ per la caratterizzazione, la valutazione della stabilità, la messa in sicurezza e la fruibilità.

Le cavità sotterranee (naturali e/o artificiali), ampiamente diffuse in Puglia, rappresentano un importante patrimonio storico-culturale-architettonico, spesso non adeguatamente valorizzato, anche in ragione della pericolosità intrinseca legata alla possibilità di sprofondamenti. Tali fenomeni di instabilità (sinkholes) rappresentano un rischio sempre più diffuso, a causa delle crescenti interazioni tra cavità ed ambiente antropizzato. Il lavoro discute i risultati del progetto di ricerca PRIORITA’ (PRogetto IntegratO di mitigazione del RIschio da sprofondamento di caviTA’) finalizzato ad offrire un contributo innovativo per la mitigazione del rischio da sinkholes. Esso è stato articolato con attività che spaziano dalla catalogazione delle cavità, alla definizione di procedure sulla stabilità, alla messa a punto di tecnologie di messa in sicurezza e, infine, alla valorizzazione. Una prima fase di studio è stata condotta alla scala del centro urbano, e una seconda su singole cavità, per individuare procedure metodologiche innovative per il rilievo, la valutazione della stabilità, il monitoraggio in sito, la sperimentazione di tecniche di messa in sicurezza efficaci ed a basso impatto, e la valutazione storico-culturale-economica per una adeguata valorizzazione. I metodi sono stati sperimentati in due siti di studio: Canosa di Puglia, caratterizzata da numerose cave sotterranee di estrazione della calcarenite, e Massafra, con varie tipologie di cavità della civiltà rupestre